Aids To Forensic Medicine And Toxicology Part 11

IV.--EVIDENCE OF POISONING

It may be inferred that poison has been taken from consideration of the following factors: Symptoms and post-mortem appearances, experiments on animals, chemical a.n.a.lysis, and the conduct of suspected persons.

1. _Symptoms_ in poisoning usually come on suddenly, when the patient is in good health, and soon after taking a meal, drink, or medicine. Many diseases, however, come on suddenly, and in cases of slow poisoning the invasion of the symptoms may be gradual.

2. _Post-Mortem Appearances._--These in many poisons and cla.s.ses of poisons are characteristic and unmistakable. The post-mortem appearances peculiar to the various poisons will be described in due course.

3. _Experiments on Animals._--These may be of value, but are not always conclusive.

4. _Chemical a.n.a.lysis._--This is one of the most important forms of evidence, as a demonstration of the actual presence of a poison in the body carries immense weight. The poison may be discovered in the living person by testing the urine, the blood abstracted by bleeding, or the serum of a blister. In the dead body it may be found in the blood, muscles, viscera--especially the liver--and secretions. Its discovery in these cases must be taken as conclusive evidence of administration. If, however, it be found only in substances rejected or voided from the body, the evidence is not so conclusive, as it may be contended that the poison was introduced into or formed in the material examined after its rejection from the body, or if the quant.i.ty be very minute it will be argued that it is not sufficient to cause death. A poison may not be detected in the body, owing to defective methods, smallness of the dose required to cause death, or to its ejection by vomiting or its elimination by the excretions.

5. _Conduct of Suspected Persons._--A prisoner may be proved to have purchased poison, to have made a study of the properties and effects of poison, to have concocted medicines or prepared food for the deceased, to have made himself the sole attendant of the deceased, to have placed obstacles in the way of obtaining proper medical a.s.sistance, or to have removed substances which might have been examined.

V.--SYMPTOMS AND POST-MORTEM APPEARANCES OF DIFFERENT CLa.s.sES OF POISONS

Whilst recognizing the fact that toxic agents cannot be accurately cla.s.sified, the following grouping may for descriptive purposes be admitted with the view of saving needless repet.i.tion:

1. =Corrosives.=--Characterized by their destructive action on tissues with which they come in contact. The princ.i.p.al inorganic corrosives are the mineral acids, the caustic alkalies, and their carbonates; the organic are carbolic acid, strong solutions of oxalic acid, and acetic acid.

_Symptoms._--Burning pain in mouth, throat, and gullet, strong acid, metallic or alkaline taste; retching and vomiting, the discharged matters containing shreds of mucus, blood, and the lining membrane of the pa.s.sages. Inside of mouth corroded. There are also dysphagia, thirst, dyspnoea, small and frequent pulse, anxious expression, shock.

Death may result from shock, destruction of the parts--_e.g._, perforation of stomach or duodenum, suffocation; or some weeks subsequently death may be due to cicatricial contraction of the gullet, stomach, or pylorus.

_Post-Mortem Appearances._--Those of corrosion, with corrugation from strong contraction of muscular fibres, and followed by inflammation and its consequences. The mouth, gullet, and stomach, and in some cases the intestines, may be white, yellow, or brown, shrivelled and corroded. The corrosions may be small, or may extend over a very large surface.

Sometimes considerable portions of the lining membrane of the gullet or stomach may be discharged by vomiting or by stool. Beyond the corroded parts the textures are acutely inflamed. The stomach is filled with a yellow, brown, or black gelatinous liquid or black blood, and may in rare cases be perforated.

2. =Irritants.=--These are substances which inflame parts to which they are applied. The cla.s.s includes mineral, animal, and vegetable substances, and contains a larger number of poisons than all the other cla.s.ses together. Irritants may be divided into two groups: (1) Those which destroy life by the irritation they set up in the parts to which they are applied; (2) those which add to local irritation peculiar or specific remote effects. The first group includes the princ.i.p.al vegetable irritants, some alkaline salts, some metallic poisons, etc.; and the second comprises the metallic irritants, the metalloids (phosphorus and iodine), and one animal substance, cantharides.

_Symptoms._--Burning pain and constriction in throat and gullet, pain and tenderness of stomach and bowels, intense thirst, nausea, vomiting, purging and tenesmus, with b.l.o.o.d.y stools, dysuria, cold skin, and feeble and irregular pulse. The vomit consists at first of the food, then it becomes bile-stained, and later dark coffee-grounds in appearance, due to extravasation of blood from the over-distended vessels in the gastric mucous membrane. Death may occur from shock, convulsions, collapse, exhaustion, or from starvation on account of chronic inflammation of the gastro-intestinal mucous membrane.

_Post-Mortem Appearances._--Those of inflammation and its consequences.

Coats of stomach, fauces, gullet, and duodenum, may be thickened, black, ulcerated, gangrenous, or sloughing. Vessels filled with dark blood ramify over the surface. Acute inflammation is often found in the small intestines, with ulceration and softening of mucous membrane. The r.e.c.t.u.m is frequently the seat of marked ulceration.

3. =Poisons Acting on the Brain.=--Three cla.s.ses: The opium group, producing sleep; the belladonna group, producing delirium and illusions; and the alcohol group, causing exhilaration, followed by delirium or sleep.

_Symptoms._--Of the opium group, giddiness, headache, dimness of sight, contraction of the pupils, noises in the ears, drowsiness and confusion, pa.s.sing into insensibility. Of the belladonna group, delirium, illusions of sight, dilated pupils, dry mouth, thirst, redness of skin, coma. Of the alcohol group, excitement of circulation and of cerebral functions, want of power of co-ordination and of muscular movement, double vision, mania, followed by profound sleep and coma. In the chronic form, delirium tremens.

_Post-Mortem Appearances._--In the opium group, fulness of the sinuses and veins of the brain, with effusion of serum into the ventricles and beneath the membranes. In the belladonna group, nil. In the alcohol group, signs of inflammation, congestion of brain and membranes, fluidity of blood, long-continued rigor mortis.

4. =Poisons Acting on the Spinal Cord.=--Strychnine, brucine, thebane.

The leading symptom is tetanic spasm.

5. =Poisons Affecting the Heart.=--These kill by sudden shock, syncope, or collapse. They comprise prussic acid, dilute solution of oxalic acid and oxalates, aconite, digitalis, strophanthus, convallaria, and tobacco.

6. =Poisons Acting on the Lungs.=--These have for their type carbonic acid gas and coal gas. The fumes of ammonia are intensely irritating, and may give rise to laryngitis, bronchitis, and even pneumonia. Nitric acid fumes sometimes produce no serious symptoms for an hour or more, but there may then be coughing, difficulty of breathing, and tightness in the lower part of the throat, followed by capillary bronchitis (see p. 120).

VI.--DUTY OF PRACt.i.tIONER IN SUPPOSED CASE OF POISONING

If called to a case supposed or suspected to be one of poisoning, the medical man has two duties to perform: To save the patient's life, and to place himself in a position to give evidence if called on to do so.

If life is extinct, his duty is a simple one. He should make inquiries as to symptoms, and time at which food or medicine was last taken. He should take possession of any food, medicine, vomited matter, urine, or faeces, in the room, and should seal them up in clean vessels for examination. He should notice the position and temperature of the body, the condition of rigor mortis, marks of violence, appearance of lips and mouth. He should not make a post-mortem examination without an order in writing from the coroner. In making a post-mortem examination, the alimentary ca.n.a.l should be removed and preserved for further investigation. A double ligature should be pa.s.sed round the oesophagus, and also round the duodenum a few inches below the pylorus. The gut and the gullet being cut across between these ligatures, the stomach may be removed entire without spilling its contents. The intestines may be removed in a similar way, and the whole or a portion of the liver should be preserved. These should all be put in separate jars without any preservative fluid, tied up, sealed, labelled, and initialled. All observations should be at once committed to writing, or they will not be admitted by the court for the purpose of refreshing the memory whilst giving evidence. If the medical pract.i.tioner is in doubt on any point, he should obtain technical a.s.sistance from someone who has paid attention to the subject.

In a case of attempted suicide by poisoning, is it the duty of the doctor to inform the police? He would be unwise to do so. He had much better stick to his own business, and not act as an amateur detective.

VII.--TREATMENT OF POISONING

The modes of treatment may be ranged under three heads: (1) To eliminate the poison; (2) to antagonize its action; (3) to avert the tendency to death.

1. The first indication is met by the administration of emetics, to produce vomiting, or by the application of the stomach-tube. The best emetic is that which is at hand. If there is a choice, give apomorphine hypodermically. The dose for an adult is 10 minims. It may be given in the form of the injection of the Pharmacopoeia, or preferably as a tablet dissolved in water. Apomorphine is not allied in physiological action to morphine, and may be given in cases of narcotic poisoning.

Sulphate of zinc, salt-and-water, ipecacuanha, and mustard, are all useful as emetics. Tickling the fauces with a feather may excite vomiting.

In using the elastic stomach-tube, some fluid should be introduced into the stomach before attempting to empty it, or a portion of the mucous membrane may be sucked into the aperture. The tube should be examined to see that it is not broken or cracked, as accidents have happened from neglecting this precaution. The bowels and kidneys must also be stimulated to activity, to help in the elimination of the poison.

2. The second indication is met by the administration of the appropriate antidote. Antidotes are usually given hypodermically, or, if by mouth, in the form of tablets. In the absence of a hypodermic syringe, the remedy may be given by the r.e.c.t.u.m. In the selection of the appropriate antidote, a knowledge of pharmacology is required, especially of the physiological antagonism of drugs. Antidotes may act (1) chemically, by forming harmless compounds, as lime in oxalic acid poisoning; (2) physiologically, the drug which is administered neutralizing more or less completely the poison which has been absorbed; (3) physically, as charcoal. Every doctor should provide himself with an antidote case. The various antidotes will be mentioned under their respective poisons.

3. To avert the tendency to death, we must endeavour to palliate the symptoms and neutralize the effects of the poison. Pain must be relieved by the use of morphine; inflamed mucous membrane soothed by such _demulcents_ as oils, milk, starch; stimulants to overcome collapse; saline infusions in shock, etc. In the case of narcotics and depressing agents, stimulants, electricity, and cold affusions, may be found useful. We should endeavour to promote the elimination of the poison from the body by stimulating the secretions.

VIII.--DETECTION OF POISONS

Notice the smell, colour, and general appearance, of the matter submitted for examination. The odour may show the presence of prussic acid, alcohol, opium, or phosphorus. The colour may indicate salts of copper, cantharides, etc. Seeds of plants may be found.

This examination having been made, the contents of the alimentary ca.n.a.l, and any other substances to be examined, must be submitted to chemical processes.

Simple filtration will sometimes suffice to separate the required substance; in other cases dialysis will be necessary, in order that crystalloid substances may be separated from colloid bodies.

In the case of volatile substances distillation will be required. The poisons thus sought for are alcohol, phosphorus, iodine, chloral, ether, hydrocyanic acid, carbolic acid, nitro-benzol, chloroform, and anilin. The organic matters are placed in a flask, diluted with distilled water if necessary, and acidulated with tartaric acid. The flask is heated in a water-bath, and the vapours condensed by a Liebig's condenser. In the case of phosphorus the condenser should be of gla.s.s, and the process of distillation conducted in the dark, so that the luminosity of the phosphorus may be noted.

For the separation of an alkaloid, the following is the process of Stas-Otto. This process is based upon the principle that the salts of the alkaloids are _soluble in alcohol and water_, and _insoluble in ether_. The pure alkaloids, with the exception of morphine in its crystalline form, are _soluble_ in ether. Make a solution of the contents of the stomach or solid organs minced very fine by digesting them with acidulated alcohol or water and filtering. The filtrate is shaken with ether to remove fat, etc., the ether separated, the watery solution neutralized with soda, and then shaken with ether, which removes the alkaloid in a more or less impure condition. The knowledge of these facts will help to explain the following details, which may be modified to suit individual cases: (1) Treat the organic matter, after distillation for the volatile substances just mentioned, with twice its weight of absolute alcohol, free from fusel oil, to which from 10 to 30 grains of tartaric or oxalic acid have been added, and subject to a gentle heat. (2) Cool the mixture and filter; wash the residue with strong alcohol, and mix the filtrates. _The residue may be set aside for the detection of the metallic poisons, if suspected._ Expel the alcohol by careful evaporation. On the evaporation of the alcohol the resinous and fatty matters separate. Filter through a filter moistened with water. Evaporate the filtrate to a syrup, and extract with successive portions of absolute alcohol. Filter through a filter moistened with alcohol. Evaporate filtrate to dryness, and dissolve residue in water, the solution being made distinctly acid. Now shake watery solution with ether. (3) Ether from the acid solution dissolves out _colchicin_, _digitalin_, _cantharidin_, and _picrotoxin_, and traces of _veratrine_ and _atropine_. Separate the ethereal solution and evaporate. Hot water will now dissolve out _picrotoxin_, _colchicin_, and _digitalin_, but not cantharidin. (4) The remaining acid watery liquid, holding the other alkaloids in solution or suspension, is made strongly alkaline with soda, mixed with four or five times its bulk of ether, chloroform, or benzole, briskly shaken, and left to rest. The ether floats on the surface, holding the alkaloids, except morphine, in solution. (5) A part of this ethereal solution is poured into a watch-gla.s.s and allowed to evaporate. If the alkaloid is volatile, oily streaks appear on the gla.s.s; if not volatile, crystalline traces will be visible. If a volatile alkaloid, add a few pieces of calcium chloride to ethereal solution to absorb the water; draw off the ethereal solution with a pipette, allow it to evaporate, and test the residue for the alkaloids, conine and nicotine.

If a fixed alkaloid, treat the acid solution with soda or potash and ether, evaporate ethereal solution after separation, when the solid alkaloid will be left in an impure state. To purify it, add a small quant.i.ty of dilute sulphuric acid, and, after evaporating to three-quarters of its bulk, add a saturated solution of carbonate of potash or soda. Absolute alcohol will then dissolve out the alkaloid, and leave it on evaporation in a crystalline form.